Since laminated glass generates only a small amount of scattering glass fragments even when subjected to external impact and broken, laminated glass is excellent in safety. As such, the laminated glass is widely used for automobiles, railway vehicles, aircraft, ships, buildings and the like. The laminated glass is produced by sandwiching an interlayer film for laminated glass between a pair of glass plates.
When laminated glass is used as a windshield of a vehicle such as an automobile, the head of an occupant of the vehicle sometimes collides with the windshield when the vehicle is involved in an accident or the like. When the head of an occupant collides with the windshield, the occupant penetrates through the windshield and sometimes jumps out to the outside of the vehicle. For the purpose of protecting the safety of an occupant, it is preferred that the occupant be prevented from penetrating through the windshield even if the head of the occupant collides with the windshield.
Moreover, the regal regulation on head protection for a pedestrian has been started in various countries, the head protection has been reinforced and the regulation on leg protection has been supplementarily added. At the time of a collision between a vehicle and a pedestrian, as a portion by which a fatal wound is inflicted on the pedestrian, the head is the most frequent portion. In Japan, a testing method for digitizing the injury to a head is prescribed. While assuming a collision of the head of a pedestrian with a windshield or the like, a dummy made in imitation of the adult human head (a headform impactor) is shot from a testing machine against an object and the impact received by the headform impactor is measured to be evaluated as the head injury criteria (HIC).
There have hitherto been many windshields with an HIC of greater than 1000. On the other hand, in recent years, it has been announced that there are windshields with an HIC of 1000 or less. Moreover, in recent years, a vehicle mounted with an air bag for pedestrian protection has been developed, and the HIC is remarkably lowered.
For example, the following Patent Document 1 discloses laminated glass with an HIC of 1000 or less. Moreover, the following Patent Document 2 discloses laminated glass with which, at the time of a collision with a collision object, the reaction force received by the collision object from the glass can be reduced.